Sakshi Singh, Prabhakar Singh, Nitesh Prasad, Savita Singh, Avinash Singh, Pankaj Kumar Singh, Arvind K Singh, Devashish Rath, Ravi K Asthana
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引用次数: 0
Abstract
Dunaliella salina is a geographically distinct, green alga without a rigid cell wall recognized as a model system for halotolerance. In this study, D. salina strains of the Indian origin isolated from the Sambhar Lake, Rajasthan, were initially cultured optimally at a 0.5 M NaCl level, and these cultures were exposed to 1-2 M NaCl for up to 2 h for transcriptomic analyses. The cells did not accumulate substantial levels of intracellular Na+. Reduced photosynthetic efficiency was observed at 2 h with an Fv/Fm ratio (~0.2) and thereafter reached a maximum on the 10th day. Concurrently, elevated levels of proline and malondialdehyde (MDA) were also detected at higher salt concentrations, suggesting the initiation of a stress response. The transcriptomic study revealed that amino acid biosynthesis pathways, along with pyruvate and carbohydrate metabolism-related genes, were significantly enriched in 0.5 M versus 2 M NaCl-grown D. salina cells at 2 h. Downregulated genes were mainly related to cytoskeletal and microtubule proteins as owing to the loss of flagellar structures at 2 h. There was a change in the carbon flux because of the upregulation of key genes concerned with glyoxylate and TCA cycles, along with fatty acid metabolism, contributing to the remodeling of membrane lipids, thereby supporting membrane integrity. The upregulated differentially expressed genes (DEGs) were validated through qRT-PCR for the photosynthetic apparatus, antioxidative defense, ion homeostasis, and protein translocation and folding. The metabolomic profile under long-term (10th day) acclimation showed the upregulation of secondary metabolites and sterols. Therefore, the altered expression of genes indicated that D. salina strains tolerated elevated salt levels in a specified adaptive process to attain metabolic readjustments.
Dunaliella salina是一种地理上独特的绿藻,没有坚硬的细胞壁,被认为是耐盐的模式系统。在这项研究中,从拉贾斯坦邦Sambhar湖分离的印度产的D. salina菌株最初在0.5 M NaCl水平下进行最佳培养,并将这些培养物暴露于1-2 M NaCl中长达2小时进行转录组学分析。细胞内没有大量的Na+积累。光合效率在第2 h (Fv/Fm = 0.2)时下降,第10天达到最大值。同时,在较高的盐浓度下,脯氨酸和丙二醛(MDA)水平也升高,这表明应激反应的开始。转录组学研究显示,与2 M nacl培养的D. salina细胞相比,0.5 M nacl培养2 h后,氨基酸生物合成途径以及丙酮酸和碳水化合物代谢相关基因显著富集。下调基因主要与细胞骨架蛋白和微管蛋白有关,这是由于鞭毛结构在2 h时丢失所致。碳通量的变化是由于与乙醛酸酯和TCA循环相关的关键基因以及脂肪酸代谢的上调,有助于膜脂质的重塑,从而支持膜的完整性。通过qRT-PCR验证了差异表达基因(DEGs)的上调与光合器官、抗氧化防御、离子稳态和蛋白质易位和折叠有关。长期(第10天)驯化的代谢组学分析显示,次生代谢物和甾醇含量上调。因此,基因表达的改变表明,盐芽孢杆菌菌株在特定的适应过程中耐受高盐水平,以实现代谢调整。
期刊介绍:
Physiologia Plantarum is an international journal committed to publishing the best full-length original research papers that advance our understanding of primary mechanisms of plant development, growth and productivity as well as plant interactions with the biotic and abiotic environment. All organisational levels of experimental plant biology – from molecular and cell biology, biochemistry and biophysics to ecophysiology and global change biology – fall within the scope of the journal. The content is distributed between 5 main subject areas supervised by Subject Editors specialised in the respective domain: (1) biochemistry and metabolism, (2) ecophysiology, stress and adaptation, (3) uptake, transport and assimilation, (4) development, growth and differentiation, (5) photobiology and photosynthesis.